Temperature requirements for germination and emergence of several pasture species: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours in the University of Lincoln

Abstract

Eight pasture species were sown at five dates throughout autumn. The number of seedlings to emerge was recorded daily, enabling the number of days to a level of 50% emergence to be calculated. 'Moata' Italian ryegrass was the fastest emerging grass species, followed by 'Nui' perennial ryegrass, 'Advance' tall fescue, 'Kahu' timothy, and 'Wana' cocksfoot (13.6 ,15.5, 19.4, 23.6 and 25.0 days respectively). 'Mt Barker' sub clover was the fastest clover species followed by 'Pawera' red clover and 'Huia' white clover (11.7, 11.9 and 13.5 days respectively). When the number of days to 50% emergence was converted into thermal time, it was found that species which were slow to emerge had a higher thermal time requirement than faster emerging species. Conversely, fast emerging species had a low thermal time requirement. 'Pawera' red clover had the lowest mean thermal time requirement over the five sowings (104.6 degree days) and 'Wana' Cocksfoot had the highest (217.5 degree days). The time to emergence increased with the decline in soil temperature as sowing times became later. Converting the number of days to 50% emergence to thermal time resulted in the degree days required to reach 50% emergence for each species becoming relatively constant over all sowing times. It was therefore concluded that the thermal time requirement of a species is an accurate method for predicting the time taken to emergence